Fatty acid biosynthesis in plants takes place in plastids, and closely resembles that in bacteria. The process mainly involves cyclic reactions that incorporate two-carbon units into a growing acyl chain. In the last few steps of the fatty acid synthesis cycle, a 3-ketoacyl substrate is reduced to yield a fully saturated acyl chain. The final reduction step in the process is catalyzed by enoyl-ACP reductase which converts the 2,3-trans-enoyl-ACP to the corresponding saturated acyl-ACP.
Fatty acid synthesis is an important metabolic pathway, since fatty acids are essential components of plant membranes and seed oils, among others. The fatty acid composition of plant membranes is thought to be an important factor in responding to environmental stress. Accordingly the availability of nucleotide sequences encoding enoyl-ACP reductase provides a means to manipulate fatty acid composition, and consequently, to improve plant response to stress and seed oil composition, both of which are important agronomic characteristics.
Since fatty acids are essential to plant growth and development, inhibiting enoyl-ACP reductase can lead to inhibition of plant growth and development. Indeed, Arabidopsis plants with a defective enoyl-ACP reductase gene exhibit premature cell death and dramatic alterations in plant morphology which include chlorotic and curly leaves, distorted siliques, premature senescence of primary inflorescences, reduced fertility, and semidwarfism (Mou et al. (2000) Plant Cell 12:405–417). Also, the antibacterial compound triclosan and the antitubercular drug isoniazid have enoyl-ACP reductase as their molecular target (Blanchard (1996) Annu. Rev. Biochem. 65:215–239; Suguna et al. (2001) Biochem. Biophys. Res. Commun. 283:224–228). Accordingly, the nucleotide sequences disclosed herein provide a starting point for herbicide and fungicide discovery and design.